Kyoko FUJITA

Abstract:

Misfolded proteins form protein aggregates and it is hard to dissolve in aqueous buffer solutions. Some denaturants such as guanidine hydrochloride and urea are usually used to dissolve these protein aggregates in the refolding process. Excess amount of denaturants, however, prevent proteins from refolding, and prevent activity recovery even after dialysis or dilution. Furthermore, re-aggregation of protein occurs at high rate in the dialysis step. Development of re-naturation methods have been desired for a long time. Hydrated ionic liquids (Hy ILs), which have been reported as a potential solvent to stabilize proteins and enzymes [1], are expected to provide a matrix for re-naturation of aggregated proteins [2]. In this study, we have analysed the effects of component ion and water content on the dissolution followed by refolding behaviour of aggregated proteins in Hy ILs.
Aggregated concanavaline A (Con A), a sugar chain recognition protein, was prepared by heating at 70°C for 10 minutes. ILs, which have different component structures, were mixed with aggregated Con A. The solubility and folding state of Con A in Hy ILs were measured with fluorescence spectroscopy. The solubility of aggregated Con A was affected by cation structure. Furthermore, the solubility of aggregated Con A was decreased with the increase of water molecules in Hy ILs [3]. In Hy ILs composition of selected cations and anions resulted in the aggregation of Con A, showing strong solubility properties, as well as refolding behaviour. Dissolved Con A in some Hy ILs showed recovery of the binding ability of the sugar chain after dilution with the buffer.

1. K. Fujita, D. R. McFarlane, M. Forsyth, Chem Commun (2005) 4804-4806.
2. K. Fujita, M. Kajiayma, Y. Liu, N. Nakamura, and H. Ohno, Chem Commun 52 (2016) 13491-13494.
3. K. Fujita, R. Nakano, R. Nakaba, N. Nakamura, and H. Ohno, Chem Commun 55 (2019) 3563-3676.